#include <bits/stdc++.h>
#include <semaphore>
using namespace std;


class Single{

    private:
    Single(){
        
        cout<<"Single()"<<endl;
    }
    Single(const Single&)=delete;
    public:
    static Single& GetInstance()
    {
        //C++11之前静态对象的创建线程不安全
        //C++11以及之后时线程安全的
        static Single s;
        return s;
    }
};


int main()
{
    return 0;
}